There are various types of musical work resources in the art such as electronic data files of music scores, sheets of music pieces and audio signals of performed musical numbers. In order to automatically play music according to such a musical work resource, such a musical work resource will have to be converted to some music playing data file (e.g. MIDI data file) to control a tone generator for generating musical tone signals for a musical performance.
A music score data file is a data file compiled from an existing music score based on predetermined rules according to the musical grammar, and includes data defining notes of the music together with data representing staves, clefs, key signatures, time signatures, tempo marks, dynamic marks, repeat signs, ornamentations, bowing signs, etc. as well as their locations to be exhibited, and also data indicating punctuations of measures, tiers and pages, and also graphical data representing images of the signs and the marks.
By executing a specialized application program, a music score image data file can be composed to display on a display screen or print on a sheet of paper by a printer in a quality close to prevailing music score prints based on such a compiled electronic music score data file. For example, there are services for downloading electronic music score data files according to the ScorchXF™ protocol, and there are also services of providing specialized application programs for displaying or printing music scores based on such an electronic music score data file. See “FREE ScorchXF™ Digital Delivery,” at Internet <URL: www.yamahamusicsoft.com/scorch/free_sample.php>, which was actually available on line on Sep. 10, 2002.
A music playing data file such as a MIDI protocol data file can be extracted (and compiled) from the data contained in such an electronic music score data file to represent notes of the music. The MIDI data file also contains data for designating tone generation time points, and can be stored or transmitted in a file format of the SMF (Standard MIDI File) or a file format specific to a sequencer software program. In case a MIDI data file is transmitted in real time, there is no need of data for designating the tone generation time points.
On the other hand, there are OCR application programs with which a scanner converts a printed music sheet into a music score image data file which can be processed by a personal computer so that a music playing data file or performance data file (e.g. MIDI data file) is extracted from the music score image data file. Also known in the art is a method of analyzing a melody part as well as other performance parts with respect to an audio data file as provided by means of an audio compact disc (CD), etc. thereby extracting a music playing data file (e.g. MIDI data file). The use of such programs for extracting a music playing data file (e.g. MIDI data file) from above mentioned various musical work resources will make it readily available for a user to acquire a music playing data file (e.g. MIDI data file) and to copy the same freely.
However, the music work resources such as electronic music score data files, printed music sheets and audio data files are generally under the protection of copyright of lyricists, composers, data compilers, performers, etc. It is, therefore, illegal for a user to freely copy (and so forth) such an extracted music playing data file without permission. Even if the extraction of a music playing data file is permitted by the copyright owner of the original music, what is permitted to the person who has purchased the provided music data file is to use or copy the performance data file for personal use only, and not to bulletin on a web site or to deliver to other people. Thus, there is a need for an electronic music data handling system in which a music playing data file as extracted from a provided musical work resource should not be copied and used freely.